The present invention relates to mechanisms for locking movable parts to and for permitting movements of such parts relative to second parts which may but need not be stationary. More particularly, the invention relates to improvements in devices for actuating such mechanisms. Still more particularly, the invention relates to improvements in devices for actuating mechanisms which can releasably secure mobile first frames (e.g., sashes) to second frames, e.g., for actuating mechanisms which can releasably secure sashes to window- or door frames.
Mechanisms of the above outlined character are installed in one of the two frames (e.g., in a stationary door- or window frame, and can receive motion in response to proper manipulation of a knob, lever or a like handle to thereby terminate the locking connection between the two frames (so that the mobile frame can be moved to a partly open or to a fully open position relative to the second frame and thereupon back to the position for releasably locking the two frames to each other). In many instances, the connection between a handle and the locking- or unlocking mechanism will comprise one or more reciprocable motion receiving elements which are mounted in one of the frames and are set in motion in response to manipulation (e.g., pivoting or turning) of the handle. The handle can be pivotably mounted in a housing which is affixed to one of the frames and enables the handle to turn about an axis which is normal to the adjacent side of the frame serving to support the housing. The handle can transmit motion to a plate-like member which, in turn, transmits motion to the motion receiving element or elements of the mechanism.
German Utility Model No. 1 745 936 of Aluminium-Walzwerke Singen GmbH (published Mar. 20, 1957) discloses a device which can releasably lock a sash to a door- or window frame and wherein the handle constitutes one arm and a plate member constitutes another arm of a two-armed lever. The plate member is bifurcated and extends from a housing which contains the pivot for the two-armed lever. The bifurcated portion of the plate member can receive a pin which transmits motion to the motion receiving element or elements in response to pivoting of the two-armed lever relative to the housing. The lever can be pivoted to any one of several positions in each of which the mechanism assumes a different condition (e.g., a locking and an unlocking state). The extent of movability of the motion receiving element or elements in the device which is disclosed in the German Utility Model is limited, primarily because the dimensions of the bifurcated portion of the plate member must be increased if such element or elements are to be moved through greater distances. On the other hand, the dimensions of the two-armed lever cannot be increased at will because this would detract from the appearance of the device and would prevent installation of such device in an available frame. Moreover, the plate member cannot be pivoted to any desired number of satisfactory angular positions because a large force would be required to pivot the handle in order to lock the mobile frame to or to unlock the mobile frame from the other frame. As a rule, the force which is required to pivot the handle and the associated plate member will increase if the extent of angular displacement of the handle is increased. Such angular displacement takes place in a plane normal to the plane of the adjacent side of that frame which carries the housing for the pivot member supporting the two-armed lever. The mechanism is likely to block if the angular displacement of the lever is increased beyond a certain value. Therefore, the device which is disclosed in the German Utility Model is useful only when the extent of angular displacement of the two-armed lever between its end positions is relatively small, i.e., if the extent of linear or other displacement of the motion receiving element or elements is also small. This is unacceptable in many types of locking-unlocking mechanisms for door- or window sashes. The two-armed lever wherein the plate member is compelled to share all angular movements of the handle contributes to the bulk of the aforedescribed conventional device.
German Utility Model No. 1 822 045 of Grossmeyer (published Aug. 30, 1960) discloses a locking device for window sashes which are made of aluminum. A handle is pivotable about an axis defined by a pivot member in a housing which is outwardly adjacent a frame. The handle constitutes one arm of a two-armed lever which further includes a bifurcated plate-like second arm in engagement with a profiled motion transmitting part which is shiftable in the frame in response to pivoting of the handle to thereby displace a motion receiving element in the frame. The second arm of the lever is confined in the housing which latter further receives a major part of the profiled motion transmitting member. All this contributes to the bulk of the device of Grossmeyer. The drawbacks of the just described device are similar to those outlined hereinbefore in connection with the device of Aluminium-Walzwerke Singen GmbH.
German Utility Model No. 71 07 673 of Friedrich Hahn GmbH (published Jun. 24, 1971) discloses a device wherein the handle is pivotable in a plane which is parallel to the adjacent exposed side of a frame. Such frame supports a rather large and bulky housing which confines all or nearly all parts serving to displace a motion receiving element in response to pivoting of the handle. Furthermore, it is necessary to exert a large force in order to move the motion receiving element to certain positions relative to the frame.